The deal is being made by Bezos alone, without involvement from Seattle-based Amazon.

Donald Graham, chairman and CEO of Washington Post Co., said the board of directors decided to sell the company's newspaper publishing business "only after years of familiar newspaper-industry challenges made us wonder if there might be another owner who would be better for the Post."

“Everyone at the Post Co. and everyone in our family has always been proud of the Washington Post — of the newspaper we publish and of the people who write and produce it,” Graham said. "Jeff Bezos’ proven technology and business genius, his long-term approach and his personal decency make him a uniquely good new owner for the Post.”

It's an unexpected move for Bezos, a self-made billionaire whose far-flung interests -- among them unearthing old rocket engines from the bottom of the ocean and inventing a futuristic clock -- haven't seemed to include traditional print media.

In a statement, Bezos said: "I understand the critical role the Post plays in Washington, D.C., and our nation, and the Post’s values will not change. Our duty to readers will continue to be the heart of the Post, and I am very optimistic about the future.”

Bezos said Katharine Weymouth, CEO and publisher of the Post; Stephen P. Hills, president and general manager; Martin Baron, executive editor; and Fred Hiatt, editor of the editorial page would continue in their current roles.

“With Mr. Bezos as our owner, this is the beginning of an exciting new era,” Weymouth said. “I am honored to continue as CEO and publisher. I have asked the entire senior management team at all of the businesses being sold to continue in their roles as well.”

The transaction covers the Washington Post and other publishing businesses, including the Express newspaper, the Gazette Newspapers, Southern Maryland Newspapers, Fairfax County Times, El Tiempo Latino and Greater Washington Publishing.

Slate magazine, TheRoot.com and Foreign Policy are not part of the transaction and will remain with Washington Post Co., as will the WaPo Labs and SocialCode businesses, the company’s interest in Classified Ventures and certain real estate assets, including the headquarters building in downtown Washington.

Washington Post Co., which also owns Kaplan, Post-Newsweek Stations and Cable ONE, will be changing its name in connection with the transaction; no new name has yet been announced.

The deal is expected to close later this year.

The Washington Post began publishing Thursday, Dec. 6, 1877, when the newspaper contained four pages and cost 3 cents a copy.

The Post is the third major news publication to be sold in as many days. Over the weekend, Red Sox owner John Henry bought the Boston Globe for $70 million. And Newsweek announced it had sold itself to digital news company IBT Media for an undisclosed amount.

“The paper’s duty will remain to its readers and not to the private interests of its owners,” he said. “We will continue to follow the truth wherever it leads, and we’ll work hard not to make mistakes. When we do, we will own up to them quickly and completely.”

As of March 31, the Post had an average total circulation of 474,767, making it the seventh-largest daily newspaper in the U.S., according to the Alliance for Audited Media. That was down 6.5% from a year earlier.

The deal was announced after the markets closed. In after-hours trading, shares jumped 4.4% to $593.95 as of 2 p.m. PDT. During regular trading, shares rose $8.75, or 1.6%, to $568.70.